package Luoguo;

import java.util.Scanner;

public class test1 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double s=sc.nextDouble();
        double s1=0;
        double i=2.0;
        int count=0;
        while (s1<=s){
            count++;
            s1+=i;
            i=i*0.98;
        }
        System.out.println(count);
    }
}
